Scandium Oxide Production Process

Scandium oxide production process
The chemical formula of scandium oxide is Sc2O3. Nature: white solid. It has cubic structure of rare earth sesquioxide. Density 3.864. Melting point 2403 ℃± 20 ℃. Insoluble in water, soluble in hot acid. It is prepared by thermal decomposition of scandium salt. It can be used as evaporation material for semiconductor coating. Make variable wavelength solid-state lasers, high-definition television electron guns, metal halide lamps, etc.
Scandium oxide (Sc2O3) is one of the most important products in scandium products. Its physical and chemical properties are similar to those of rare earth oxides (such as La2O3, Y2O3 and Lu2O3), so the production methods used in production are very similar. Sc2O3 can produce scandium metal (Sc), products of different salts (ScCl3, ScF3, ScI3, Sc2 (C2O4) 3, etc.) and various scandium alloys (Al-Sc, Al-Zr-Sc series). These scandium products have practical technical value and good economic results. Due to some characteristics of Sc2O3, it has been widely used in aluminum alloys, electric light sources, lasers, catalysts, activators, ceramics and aerospace, and its development prospects are very broad.
In the 1970s, China began to develop Sc2O3 products, and kilogram products entered the market. In the 1980s, China's production of Sc2O3 reached a climax, with the output reaching more than 100 kg, mainly exported to Japan and the United States. Since the 1990s, Russia has produced a large number of Sc2O3 products and thrown them into the international market at a low price, which has seriously impacted the production of scandium oxide in China, making the production of Sc2O3 at a low point, and many production lines have been down, making China's capacity and output in a shrinking state. However, in recent years, the development of Sc-Al alloy and electric light source materials in China has promoted the development of Sc2O3 industrial production. China is rich in scandium resources. It is reported that the industrial reserves of scandium in the world are about 2 million tons at present, and there are about 600000-650000 tons in China, accounting for about 30% of the world's total content. After years of research and production practice, the production technology and equipment for extracting Sc2O3 from scandium-containing raw materials include the following methods:
① Extraction method. It is widely used in production and has the characteristics of large output, good quality, high recovery rate, low cost and continuous operation in production.
② Ion exchange method. It is also often used in production. It has the characteristics of low yield, high purity, low yield, high cost and long production cycle.
③ Extraction resin chromatography. It has the characteristics of short production cycle, high purity, high yield and low cost.
④ Liquid membrane extraction method. It is a new separation technology combining membrane separation and liquid-liquid extraction. But there is no production practice at present. Some people have used emulsion liquid membrane to enrich Sc from 60mg/L to 1400mg/L after primary extraction. From the perspective of Sc2O3 extraction in China for many years, the first two processes are almost adopted
Technology (extraction and ion exchange). [2]
extraction method
(1) The process of producing scandium oxide from scandium concentrate by extraction method: the scandium concentrate is dissolved with hydrochloric acid to obtain ScCl3 solution, and then the impurities such as titanium and iron are purified. Purified liquid is used as raw material. 50% TBP and kerosene were used as extractant. The prepared material solution and extractant are put into the extraction tank to extract scandium. After acid washing and distilling water to extract scandium, the pure scandium-containing solution (ScCl3 solution) is obtained and then precipitated with oxalic acid. After drying and burning, the pure Sc2O3 product is obtained. The main process is: scandium concentrate - acid dissolution - purification - TBP extraction of scandium - acid washing - stripping of scandium - oxalic acid precipitation - drying - burning - packaging - warehousing (pure Sc2O3 products).
Main equipment: acid dissolving tank, extraction tank, sedimentation tank, burning furnace, packaging machine, etc.
Ion exchange method
Technological process: tungsten waste slag (containing Sc2O378g/t~377g/t) is used as raw material. It is dissolved in hydrochloric acid and filtered, and the feed liquid is purified to obtain ScCl3 clean solution, which is used as the feed liquid for ion exchange after mixing. Prepare the adsorption column and separation column for use. The feed liquid (ScCl3 liquid) flows into the adsorption column from the upper end of the column and reaches Sc3+saturation for use. After connecting the adsorption column with the separation column, the eluent will flow into and through the separation column from the top of the adsorption column. After the last separation column stably flows out of the ScCl3 solution, the ScCl3 solution (pure ScCl3 solution) can be continuously received into the collecting container, and then the acidity is adjusted, and then the oxalic acid is used for precipitation, filtration, drying and burning to form pure Sc2O3 product. The main process is as follows: tungsten waste residue - acid dissolution - purification - adsorption column - leaching - receiving ScCl3 solution - adjusting acid - precipitating scandium - drying - burning - packaging - warehousing (pure Sc2O3 product).
Main equipment: acid dissolving tank, adsorption column, separation column, sedimentation tank, burning furnace, packaging machine, etc.
Extraction resin chromatography
Technological process: dissolve the chlorinated smoke and dust with HCl, and then purify it to make ScCl3 feed liquid. Scandium is extracted in the extraction tank with 50% TBP-kerosene extractant, impurities are pickled, and scandium is extracted back to obtain pure Sc-Cl3 solution, then Sc is precipitated with H2C2O4, and pure Sc2O3 is obtained by burning. The main process is as follows: oxidation fume - hydrochloric acid dissolution - purification - net ScCl3 solution - extraction - acid washing - stripping - precipitation - burning - packaging - warehousing (pure Sc2O3 product).
Liquid membrane extraction
Take titanium white waste liquid (containing Sc2O325g/m3) as raw material. In the sulfuric acid medium system using P204 kerosene as the extractant, scandium is extracted from the feed liquid in the extraction tank. After the impurities are removed by acid washing with H2SO4 and H2O2, the scandium is extracted back with NaOH solution to form Sc (OH) 3 concentrate. The Sc (OH) 3 is dissolved in hydrochloric acid to form ScCl3 solution. The oxalic acid precipitates scandium (twice) and burns it. The package is pure Sc2O3 product. The main process is: titanium dioxide waste liquor - preparation - extraction - pickling - stripping - sc (OH) 3 product - dissolution - precipitation - burning - packaging - warehousing (pure Sc2O3 product).